IONIC POLYMERS 141
-
(1) Friedel Crafts
°
(9J
II (2) Na2S03
CI CCH 2 CI
(3) Reduction
CH 2 CH 2 S03 H
Cellulose-based ion-exchange polymers have been investigated. They are
made by reacting ionic reagents with the hydroxyl groups present in the
cellulose, e.g. to form sulpho-ethyl cellulose-CH 2 CH 2S0 3 H.
6.11 Polyelectrolytes based on carboxylates
Polyacrylate-type homopolymers are the most ionic of the organic polymers.
They are water-soluble and produce aqueous solutions with unusual and
useful physical properties. They are generally made by free-radical poly-
merization in aqueous solution. Very high molecular weights (e.g. 4 x 106 )
can be achieved which give very viscous solutions. Polyacrylic, polymeth-
acrylic and polyitaconic acids are the three main types:
H CH 3 CH 2COOH
I I I
-CH2-C- -CH2-C- -CH2-C-
I I I
COOH COOH COOH
13.9 equiv./kg 11.6 equiv./kg 15.4 equiv./kg
acrylic methacrylic itaconic
Aqueous solutions or dry powders of these materials are commercially
available. Versicols™ (Allied Colloids) which are homopolymers of acrylic
or methacrylic acids or their copolymers with acrylamide are sold in either
form. Texigels™ (Scott Bader) are aqueous solutions of similar materials
and Texipols™ are their dispersions in an organic medium which can be
pumped and compounded without the gelation and viscosity problems
sometimes encountered when these kinds of polymer are manipulated in
water. Carbopols™ (B.F. Goodrich) are six grades of polyacrylic acid of varied
molecular weight. Carbosets™ (B.F. Goodrich) are acrylic copolymers and
have a similar carboxyl content but generally can be dissolved in alkaline
solutions. They are used mainly in coating applications; one such uses an
aqueous solution of the ammonium or morpholine salt which on heating
loses ammonia or morpholine and dries to form a water-repellent layer. They
are designed to be covalently cross-linked with epoxides and so on but some
applications use ionic cross-links made with zinc ions.
A different type of carboxylic polyelectrolyte is the structure below. It is
a hydrolysed alternating copolymer of methyl vinyl ether and maleic
-
(1) Friedel Crafts
°
(9J
II (2) Na2S03
CI CCH 2 CI
(3) Reduction
CH 2 CH 2 S03 H
Cellulose-based ion-exchange polymers have been investigated. They are
made by reacting ionic reagents with the hydroxyl groups present in the
cellulose, e.g. to form sulpho-ethyl cellulose-CH 2 CH 2S0 3 H.
6.11 Polyelectrolytes based on carboxylates
Polyacrylate-type homopolymers are the most ionic of the organic polymers.
They are water-soluble and produce aqueous solutions with unusual and
useful physical properties. They are generally made by free-radical poly-
merization in aqueous solution. Very high molecular weights (e.g. 4 x 106 )
can be achieved which give very viscous solutions. Polyacrylic, polymeth-
acrylic and polyitaconic acids are the three main types:
H CH 3 CH 2COOH
I I I
-CH2-C- -CH2-C- -CH2-C-
I I I
COOH COOH COOH
13.9 equiv./kg 11.6 equiv./kg 15.4 equiv./kg
acrylic methacrylic itaconic
Aqueous solutions or dry powders of these materials are commercially
available. Versicols™ (Allied Colloids) which are homopolymers of acrylic
or methacrylic acids or their copolymers with acrylamide are sold in either
form. Texigels™ (Scott Bader) are aqueous solutions of similar materials
and Texipols™ are their dispersions in an organic medium which can be
pumped and compounded without the gelation and viscosity problems
sometimes encountered when these kinds of polymer are manipulated in
water. Carbopols™ (B.F. Goodrich) are six grades of polyacrylic acid of varied
molecular weight. Carbosets™ (B.F. Goodrich) are acrylic copolymers and
have a similar carboxyl content but generally can be dissolved in alkaline
solutions. They are used mainly in coating applications; one such uses an
aqueous solution of the ammonium or morpholine salt which on heating
loses ammonia or morpholine and dries to form a water-repellent layer. They
are designed to be covalently cross-linked with epoxides and so on but some
applications use ionic cross-links made with zinc ions.
A different type of carboxylic polyelectrolyte is the structure below. It is
a hydrolysed alternating copolymer of methyl vinyl ether and maleic
